JPC SYSTEMIC PATHOLOGY
HEMOLYMPHATIC SYSTEM
April 2018
H-V12 (NP)

Signalment (JPC #2415492): Adult male African green monkey (Cercopithecus aethiops)

HISTORY: One of six African green monkeys inoculated intraperitoneally with 1000 plaque-forming units of Ebola (Zaire) virus.

HISTOPATHOLOGIC DESCRIPTION:

  1. Spleen: Diffusely, white pulp has a marked paucity of mature small lymphocytes affecting both follicles and periarteriolar lymphoid sheaths with scattered lymphocytolysis, increased numbers of tingible body macrophages that often contain cellular and karyorrhectic debris, and prominent perifollicular hemorrhage. Diffusely the red pulp is expanded by abundant fibrin, admixed with karyorrhectic debris (necrosis) and few scattered macrophages and neutrophils.  Splenic veins are lined by hypertrophic reactive endothelium.
  2. Liver: Affecting up to 40% of liver parenchyma are multifocal and random areas characterized by hepatocytes which are swollen and pale with vacuolated cytoplasm (degeneration) or shrunken and angular with pyknotic or lytic nuclei (necrosis). Surrounding sinusoids are mildly expanded by fibrin, few neutrophils, monocytes and lymphocytes. Occasionally, hepatocytes and monocytes contain round, up to 10 um in diameter, eosinophilic intracytoplasmic viral inclusions, and vessels occasionally contain fibrin thrombi.

MORPHOLOGIC DIAGNOSES:

  1. Spleen: Lymphoid depletion, diffuse, severe, with lymphocytolysis, perifollicular hemorrhage, extensive red pulp fibrin deposition, and necrosis, African green monkey (Cercopithecus aethiops), primate.
  2. Liver: Hepatocellular degeneration and necrosis, multifocal and random, with mild subacute inflammation, fibrin thrombi, and hepatocellular and monocytic intracytoplasmic eosinophilic viral inclusion bodies.

ETIOLOGIC DIAGNOSIS: Filoviral splenitis and hepatitis

CAUSE: Ebola virus, Zaire subtype

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

Hemorrhagic fever viruses:

COMPARATIVE PATHOLOGY:

Animal models include guinea pigs, hamsters, mice and rabbits:

tissues, hepatic necrosis, vasculitis, hemorrhage, and extravascular fibrin accumulation

REFERENCES:

  1. Bell TM, Bunton TE, et al. Pathogenesis of Bolivian hemorrhagic fever in Guinea pigs. Vet Pathol. 2016; 53(1):190-199.
  2. Bell TM, Shaia CI, Bunton TE, Robinson CG. Pathology of experimental Machupo Virus infection, Chicava strain, in Cynomolgus Macaques (Macaca fascicularis) by intramuscular and aerosol exposure. Vet Pathol. 2015; 52(1):26-37.
  3. Bowen RA. Filoviridae. In: MacLachlan NJ, Dubovi EJ, eds. Fenner’s Veterinary Virology. 4th ed.
  4. London, UK: Academic Press; 2011: 343-348.
  5. Twenhafel NA, et al. Experimental aerosolized guinea pig adapted Zaire Ebolavirus (Variant: Mayinga) causes lethal pneumonia in Guinea pigs. Vet Pathol. 2015; 52(1):21-25.
  6. Twenhafel NA, Mattix MD, Johnson JC, Robinson CG, Pratt WD, et al. Pathology of experimental aerosol Zaire Ebolavirus infection in Rhesus Macaques. Vet Pathol. 2012; 50(3): 514-529.
  7. Wachtman L, Mansfield K. Viral diseases of nonhuman primates. In: Abee CH, Mansfield K, Tardiff S, Morris T, eds. Nonhuman Primates in Biomedical Research: Diseases. 2nd San Diego, CA: Academic Press; 2012:38-41.
  8. Zumbrum EE. Mission critical: Mobilization of essential animal models for Ebola, Nipah, and Machupo virus Vet Pathol. 2015; 52(1):18-20.


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